The chemicals to be used in the present invention which comprise one or more 4-(3-butynyl)aminopyrimidine derivatives in admixture with agri-horticultural antimicrobial compounds or pesticidal compounds are not known in the art. On the other hand, many compounds having agri-horticultural antimicrobial activity (e.g., multi-site contact active compounds, nucleic acids synthesis inhibitory active compounds, mitosis and cell division inhibitory active compounds, succinate dehydrogenase inhibitory active compounds, strobilurin compounds, other electron transport chain inhibitory active compounds, amino acids and protein synthesis inhibitory active compounds, sterol biosynthesis inhibitory active compounds, signal transduction inhibitory active compounds, lipid biosynthesis inhibitory active compounds, cell wall biosynthesis inhibitory active compounds, melanine synthesis inhibitory active compounds, host plant defence inducing compounds, compounds having unknown mode of actions, biocides and other compounds having insecticidal, miticidal or nematicidal activity, such as acetylcholinesterase inhibitors (Carbamates), acetylcholinesterase inhibitors (Organophosphates), GABA-gated chloride antagonists, sodium channel modulators, nicotinic acetylcholine receptor agonists, nicotinic acetylcholine receptor allosteric activators, chloride channel activators, juvenile hormone mimics, multi-site inhibitors, selective homopteran feeding blockers, mite growth inhibitors, microbial disruptors of insect midgut membranes, mitochondrial ATP synthase inhibitory compounds, oxidative phosphorylation decoupling compounds, nicotinic acetylcholine receptor channel blockers, chitin biosynthesis inhibitory compounds, ecdysis/metamorphosis disrupting compounds, octopamine receptor agonistic compounds, electron transport chain inhibitory compounds, mitochondrial complex IV electron transport inhibitors, voltage-dependent sodium channel blockers, acetyl CoA carboxylase inhibitory compounds, ryanodine receptor modulators, and compounds having unknown mode of actions) have been either developed for commercial sale or known by being disclosed in the following non-patent document.